low voltage electromagnet

[pandia98]

Hello,

I need to make as powerful a electromagnet as possible that will be powered by a 1.5 volt battery, dimensions are unimportant. could anyone give some tips as to optimised design so that the least amount of current is consumed as possible.

thanks in advance

Best regards

Pandia

 

[israelkk]

How much force you need from the electromagnet?
How much it can weigh?

 

[EdStainless]

If you want to use less current you will need more turns. Low voltage drop coils are often wound with foil. Since volages are low you don't need much insulation. Thin copper foil and very thin plastic insulator can be wrapped to make a coil.

= = = = = = = = = = = = = = = = = = = =
Corrosion, every where, all the time.
Manage it or it will manage you.

http://www.trent-tube.com/contact/Tech_Assist.cfm

 

[pandia98]

Thankyou EdStainless for the tips. israelkk, the weight is unimportant, The force should be around the same as a small 10mm diameter, 3mm thick neodymium permanent magnet, if that is possible. The electromagnet could have a bigger face than the neodymium magnet if needed

Best regards

Pandia

 

[UKpete]

Pandia, the general rules are as follows:

1. The maximum power output of a battery circuit is obtained when the internal resistance of the battery is equal to the resistance of the load.

2. The only power consumed by the electromagnet is in the copper of the winding, so this should have as large a cross-section as possible to minimize it's resistance per unit length, thus allow the maximum number of turns.

3. I think the optimum shape for maximum field for minimum copper loss is a circular pole surrounded by a circular coil (because a circle has the highest enclosed area for a given circumference - is this true?)

3. Most important - look carefully at your magnetic circuit, maximize the proportion of the path length that is made of iron, minimize the part of path length that is in air.

4. The iron shouldn't go near to saturation i.e. keep it below about 1.5T. Some other recent threads in this forum have dealt with simple design equations for electromagnets.

 

[MJR2]

UKPete,
I made some assumptions.
Watts = 9
VDC = 1.5
Ohms=0.25
I=6
I don't work with batteries so I have no real idea if this works. But I found a source which said AAA was 0.3 and AA was 0.2 (or vis versa). I kinda doubt about 6 amps from a AA.
Anyway for fun I designed a series of coils which had about a 10mm ID and 15mm height. With AWG copper wire and film insulation we have the following. Certainly some of these (larger AWG) cannot be built.
AWG NI OD(in) Weight (lbs)
1 1431 64.2 511
2 1410 51.6 321
4 1404 32.5 127
6 1377 20.7 50
8 1361 13.0 13
10 1311 8.4 7.9
12 1267 5.3 3.1
14 1202 3.4 1.2
16 1117 2.2 0.5
18 997 1.4 0.2
20 841 0.9 0.08
22 661 0.7 0.03
24 483 0.5 0.01
It looks like somewhere in the 16-20 gage is the practical size range. And as said above foil might be a good idea. Except it should be anodized (if aluminum). As any other insulation thickness would be bad on the space factor.

Certainly a circular coil is more efficient than a rectangular core. All the wire is 'wasted' on each leg just to get a turn.

Although we assume the steel to be circular, in cross section it would look like an E on it's side. The coil is around the center leg.

It's unlikely that we could saturate a core with only 1000 NI.

 

[EdStainless]

We used to wind with foil that was 0.003"-0.008" thick, depending on the application. For low voltage you can use just about any insulation, some 0.001" plastic film would be fine. No need for a great insulator.

= = = = = = = = = = = = = = = = = = = =
Corrosion, every where, all the time.
Manage it or it will manage you.

http://www.trent-tube.com/contact/Tech_Assist.cfm

 

[pandia98]

Thanks a lot everyone, that is very helpful.

Best regards

Pandia